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Thermophysics and Aeromechanics

2013 year, number 3

1.
Investigating an annular nozzle on combustion products of hydrocarbon fuels

V.A. Levin1, N.E. Afonina1, V.G. Gromov1, G.D. Smekhov1, A.N. Khmelevsky1, and V.V. Markov1,2
1Institute of Mechanics, Lomonosov Moscow State University, Moscow, Russia
2Steklov Mathematical Institute RAS, Moscow, Russia
Keywords: jet thrust unit, Laval nozzle, annular nozzle, shock wave, combustion
Pages: 265272

Abstract >>
Full-scale and computational experiments were used to investigate the flows in the jet thrust unit with annular nozzle and deflector in the form of a spherical segment. The used working gas was the combustion products of air mixtures with acetylene, gas-phase aviation kerosene, and natural gas. Experimental studies were carried out in a hot-shot wind tunnel in the range of stagnation pressure from 0.48 to 2.05 MPa. The calculations for the cases of combustion products outflow in terrestrial and high altitude conditions were performed with the original computer program that used the Euler and NavierStokes systems supplemented by equations of chemical kinetics. It was found that the thrust of the jet module with an annular nozzle at high altitude almost twice exceeds the sound nozzle thrust, but is lesser (about 25 %) than the thrust of the ideal calculated Laval nozzle; the difference therewith decreases markedly with the decrease of flight altitude and stagnation pressure.
																								



2.
Intensification of mixing by small-size jets in ejectors with central nozzle

A.V. Sobolev
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: convergent chamber, central nozzle, mixing intensification, small-size jets, critical regime, experi-mental and computed characteristics
Pages: 273276

Abstract >>
An experimental investigation of the influence of mixing intensification by small-size jets on the startup and characteristics of a gas ejector with central nozzle and a convergent mixing chamber is carried out. It is shown that at high flow rates of the secondary gas, the critical regime is not settled because of the formation of a thick subsonic layer near the chamber wall. In these cases, a stepwise startup was done. The range of critical regimes is limited by the reloading point, at which the velocity near the chamber wall becomes sonic. The critical regime breakdown behind the reloading point occurs due to the upstream propagation of the back pressure through the subsonic layer. The mixing intensification ensures the equalization of the velocity profile and the extension of the range of critical regimes. Despite the improvement of characteristics the mixing in an ejector with the central nozzle remains incomplete. Experimental characteristics are compared with the computed ones. The mixing process is isobaric in the computation without the consideration of dissipative losses because of which the rise of the pressure of a mixture of primary and secondary gases occurs.
																								



3.
Vibration influence on a region with gas under the adiabatic and isothermal boundary conditions

P.T. Zubkov1, 2 and A.V. Yakovenko1
1Tyumen Branch of the Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Tyumen, Russia
2Tyumen State University, Tyumen, Russia
Keywords: shock wave, acoustic wave, perfect gas, oscillation frequency, oscillation amplitude
Pages: 277288

Abstract >>
The influence of vibration on the behavior of the perfect viscous gas inside a rectangular cavity is investigated numerically. The heat and mass transfer processes in gas are compared in the region under the isothermal and adiabatic boundary conditions. The problem is solved in the one-dimensional statement.
																								



4.
Simulation of a thick turbulent boundary layer via a rod grid

V.I. Kornilov and A.V. Boiko
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: simulation, experiment, incompressible turbulent boundary layer, flat plate, rod grid
Pages: 289302

Abstract >>
A possibility to simulate a thick Clauser-equilibrium incompressible turbulent boundary layer on a flat plate of finite length with the help of a grid formed by cylindrical rods was experimentally examined. A grid with rods oriented parallel to the streamlined surface proved to be an efficient tool enabling modification of the turbulent boundary layer. In most cases, at a distance of 600 rod diameters the time-average and fluctuation characteristics of the modified boundary layer exhibited values typical of a natural turbulent boundary layer. It is shown that the mean velocity profiles with artificially increased boundary-layer thickness can be represented, to a good accuracy, in terms of law-of-the-wall variables, and they can be generalized with a single dependence using an empirical velocity scale in the outside region. The use of a combined method for exerting an influence on the shear flow capable of improving the modeling procedure for turbulent velocity fluctuations in boundary layer is proposed.
																								



5.
Interference action of weakly compliant boundaries in the gradient flows

B.N. Semenov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: resistance reduction, compliant coating
Pages: 303308

Abstract >>
The conditions for possible reduction of hydrodynamic resistance by the compliant coatings are considered from two points of view: pulling the laminar flow and alteration of turbulence generation in the near-wall zone. A strong effect of the longitudinal pressure gradient and reasonability of the search for the laminarized bypass flows in the presence of compliant coatings are distinguished.
																								



6.
Experimental study of a textural transition in liquid crystals under shear stress induced by surface friction

G.M. Zharkova, V.N. Kovrizhina, and A.P. Petrov
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: shear stress, visualization and measurement, liquid crystals, textural transition
Pages: 309316

Abstract >>
Results of a study of the optical response of liquid crystals with helical supramolecular structure to surface-friction-induced shear stress in aerodynamic experiments are reported. The effect of re-orientation of molecules from confocal (light-scattering) to planar (selectively reflecting light) texture is considered. The textural transition is examined by the spectral and colorimetric methods. Dependences of the reflection spectra of the formed planar texture on time and on the mean shear-stress level were obtained. It is shown that the dependence of the texture transition time on the shear-stress level can be approximated, in a logarithmic scale, with a linear dependence; this allows using the effect for flow diagnostics.
																								



7.
Stability of axisymmetric swirl flows of viscous incompressible fluid

S.P. Aktershev and P.A. Kuibin
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: incompressible fluid, axisymmetric swirl flow, stability, method of solution
Pages: 317326

Abstract >>
A new method of solution to the problem of stability of the swirl flow of viscous incompressi-ble fluid is developed. The method based on expansion of the required function into power series of radial coordinate allows an avoidance of difficulties related to numerical integration of the system of differential equations with a singular point. Stability of the Poiseuille flow in a rotating pipe is considered as an example.
																								



8.
Investigation of pressure characteristics of a perforated membrane in an oscillating liquid flow

A.A. Kuraev and A.B. Semenov
Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: flow-rate coefficient, flow-rate dissimilarity, oscillations, pressure, cavitation
Pages: 327331

Abstract >>
Results of a parametric study of pressure characteristics of a perforated membrane in an oscillating liquid flow are reported. A diagram of an experimental facility for evaluation of the pressure produced by a perforated membrane in an oscillating flow is given.
																								



9.
Shift of the velocity of low-frequency pressure perturbations in the vapor-liquid mixture under nonadiabatic conditions

E.A. Tairov
Melentiev Energy Systems Institute SB RAS, Irkutsk, Russia
Keywords: a layer of spherical particles, vapor-liquid mixture, the equilibrium velocity of sound, non-stationary heat transfer
Pages: 333338

Abstract >>
A theoretical study of the equilibrium velocity of sound in the liquid-vapor mixture containing the close-packed layer of spherical particles has been carried out. Thermodynamic relations include a description of a non-stationary heat transfer between the mixture and particles in compression half-wave. The theoretical model allows explaining the experimentally observed significant reduction in the equilibrium velocity from its adiabatic value at the increase in vapor content of the mixture. The calculated results agree with experimental data obtained in the vertical channel at filtering the liquid-vapor mixture in a close-packed layer of spherical particles of borosilicate glass and steel.
																								



10.
The features of gas hydrate dissociation in porous media at warm gas injection

V.Sh. Shagapov, M.K. Khasanov, I.K. Gimaltdinov, and M.V. Stolpovsky
Sterlitamak Branch of Bashkir State University, Sterlitamak, Russia
Keywords: filtration, gas hydrates, frontal boundary dissociation, extended region of dissociation
Pages: 339346

Abstract >>
Results of numerical simulation of warm gas injection into a porous medium initially saturated with gas and gas hydrate, accompanied by gas hydrate dissociation, are presented. It is shown that depending on parameters at the outer boundary of the medium (permeable or impermeable to the gas flow) hydrate dissociation can occur both at the frontal boundary and in the extended region.
																								



11.
Removal of carbon dioxide from gas mixtures by wollastonite

V.S. Engelsht1 and V.Zh. Muratalieva2
1Institute of Physical Technical Problems and Material Sciences NAS KR, Bishkek, Kyrgyz Republic
2Kyrgyz State Technical University, Bishkek, Kyrgyz Republic
Keywords: wollastonite, synthesis, decomposition, carbon dioxide, burial, removal, cyclic reciprocating process
Pages: 347349

Abstract >>
Wollastonite synthesis and decomposition were analyzed from the viewpoint of thermodynamics (using the TERRA software). It is shown that wollastonite synthesis from limestone and silica takes place at a minimum content of nitrogen (10–5 N2) with a release of carbon dioxide. The synthesis temperature is ≥ 560 K. Wollastonite is decomposed in the presence of flue gas (4N2) with limestone and silica formation and burial of carbon dioxide in the form of CaCO3(c). Wollastonite decomposition temperature is ≤ 420 K. The cyclic reciprocating process for complete removal of carbon dioxide by wollastonite is suggested. Four strokes of the reciprocating system with the fixed temperatures of wollastonite decomposition ( = 300 K) and wollastonite synthesis ( = 560 K) are presented. Total energy consumption ( = 560 K) is ΔI ≈ 130 kJ/mole, 30 % of energy is spent for heating and 70 % of energy is spent for chemical reaction. This is comparable with the heat of 2 solution in ethanolamin.
																								



12.
Impingement of a vortex ring transporting admixture on a solid surface

V. Nikulin
Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia
Keywords: vortex ring, solid surface, interaction
Pages: 351354

Abstract >>
Normal impingement of a vortex ring, formed in water and transporting the coloring admixture, on a solid surface was studied experimentally. The size and shape of a trace of vortex impingement on the surface were determined. It was found that the size of trace does not depend on the speed of the vortex ring, and its shape is determined by the amount of admixture in the vortex. The connection of results with possible mechanism of annular structures formation on the ice of Lake Baikal is discussed.
																								



13.
Thermal expansion of ChS-139 steel in temperature range 20–720 °

S.V. Stankus, Yu.M. Kozlovsky, O.S. Yatsuk, and O.I. Verba
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: coefficient of thermal expansion, ChS-139 steel, solid state, high temperatures
Pages: 355358

Abstract >>
The article presents the results of investigation of thermal expansion of ChS-139 steel in the temperature range 20–720 °. Measurements were carried out by dilatometric method with DIL-402C unit manufactured by NETZSCH (Germany) with the error (1.52) × 107 K1. The approximation dependences of thermal coefficient of linear expansion on temperature have been obtained and reference tables have been calculated. The abnormal change of expansion coefficient above 550 is shown, and the explanation of the phenomenon is given.
																								



14.
PIV method for research of the structure of pulsating flow in a smooth duct

A.E. Goltsman, I.A. Davletshin, and A.A. Paereliy
Research Center for Power Engineering Problems of Kazan Scientific Center of the RAS, Kazan, Russia
Keywords: PIV measurements, pulsating flow, superimposed pulsations, velocity profiles, kinematic structure, amplitude of velocity pulsations, oscillogram of velocity values
Pages: 359366

Abstract >>
The system for PIV measurements in the flow with superimposed pulsations of the fluid (air) has been developed. Measurements of velocity and vorticity fields in a smooth duct in certain phases of superimposed pulsations have been performed. Statistics of a turbulent pulsating flow: velocity profiles, turbulent pulsations, and Reynolds stresses has been obtained.
																								



15.
Heat-transfer processes upon laser heating of inert-matrix-hosted inclusions

V.G. Kriger1, A.V. Kalenskii1, A.A. Zvekov2, I.Yu. Zykov1, and A.P. Nikitin1
1Kemerovo State University, Kemerovo, Russia
2Institute of Coal Chemistry and Chemical Materials Science SB RAS, Kemerovo, Russia
Keywords: laser radiation, melting, hot-spot model, thermal explosion
Pages: 367374

Abstract >>
A model to describe the heating of metal inclusions in inert media by a laser radiation pulse with allowance for the heat-transfer and melting processes in the matrix and inclusion materials is proposed. The time regularities of the heating of the matrix and inclusions were examined, and the dependences of the maximum temperature on the particle surface on the laser pulse energy density and on the particle radius were obtained. Approximate formulae for the maximum heating temperature and for the radius of most heated particles are proposed. We show that melting processes result in a reduction of the maximum heating temperature and in an insignificant variation of the radius of most heated particles.
																								



16.
Gas-jet method for deposition of metal nanoparticles into the fluorine-polymer matrix

M.N. Andreev1, 2, I.S. Bespalov2, and A.I. Safonov2
1Novosibirsk State University, Novosibirsk, Russia
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: gas-jet deposition, metal-polymer, silver nanoparticles, fluorine-polymer, composite coatings, optical properties, plasmon resonance
Pages: 375379

Abstract >>
The work deals with the obtaining by the vacuum gas-jet technique of the metal-polymer composites consisting of silver nanoparticles introduced into a fluorocarbon polymer matrix and the investigation of their optical properties. The dependence of the optical density in the visible range of frequencies on the structure of obtained samples has been investigated. The obtained composites are found to possess the plasmon resonance effect.
																								



17.
Physical and mathematical model of the coagulation of micron and submicron aerosols with regard for evaporation and sedimentation at ultrasonic effect

O.B. Kudryashova, A.A. Antonnikova, and S.S. Titov
Institute for Problems of Chemical and Energetic Technologies SB RAS, Biysk, Russia
Keywords: aerosol, distribution over sizes, ultrasonic effect, evaporation, coagulation, sedimentation
Pages: 381384

Abstract >>
A physical and mathematical model is proposed, which is based on the Smolukhovskys equation describing the dynamics of the variation of the distribution function of aerosol particles over their sizes with regard for ultrasonic action, evaporation (for liquid-drop aerosols), and sedimentation. The expressions are obtained for the coagulation kinetics depending on the main parameters of action, the properties of aerosol and medium: the concentration and dispersion composition of the original aerosol, viscosity and temperature of the medium, physical-chemical parameters of particles material. Computational results obtained by using the proposed model correspond to experimental data.
																								



18.
Experimental study of surface tension of ethane-methane solution in temperature range 213–283 K

V.N. Andbaeva and M.N. Khotienkova
Institute of Thermophysics UB RAS, Ekaterinburg, Russia
Keywords: surface tension, capillary constant, capillary rise method, ethanemethane solution
Pages: 385389

Abstract >>
The differential variation of the method of capillary rise was used to measure the capillary con-stant and to determine the surface tension of ethane-methane solution at “high” temperatures. Measurements were performed on the isotherms in the range of temperatures 213.15 ÷ 283.15 K at pressures up to 4 MPa. Decrease of ethane surface tension with the increase of pressure and concentration of methane in the solution is shown. The experimental data are compared with the results of surface tension calculation according to Rowlinson theory. Methane adsorption in the interface layer of solution is calculated.